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util/interpolation.lua @ 10185:02d8f475a96d
util.prosodyctl: call_luarocks function is now compatible with the list command
author | João Duarte <jvsDuarte08@gmail.com> |
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date | Wed, 31 Jul 2019 10:22:11 -0700 |
parent | 6772:805baeca56b6 |
child | 10348:3852fc91b2fc |
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-- Simple template language -- -- The new() function takes a pattern and an escape function and returns -- a render() function. Both are required. -- -- The function render() takes a string template and a table of values. -- Sequences like {name} in the template string are substituted -- with values from the table, optionally depending on a modifier -- symbol. -- -- Variants are: -- {name} is substituted for values["name"] and is escaped using the -- second argument to new_render(). To disable the escaping, use {name!}. -- {name.item} can be used to access table items. -- To renter lists of items: {name# item number {idx} is {item} } -- Or key-value pairs: {name% t[ {idx} ] = {item} } -- To show a defaults for missing values {name? sub-template } can be used, -- which renders a sub-template if values["name"] is false-ish. -- {name& sub-template } does the opposite, the sub-template is rendered -- if the selected value is anything but false or nil. local type, tostring = type, tostring; local pairs, ipairs = pairs, ipairs; local s_sub, s_gsub, s_match = string.sub, string.gsub, string.match; local t_concat = table.concat; local function new_render(pat, escape, funcs) -- assert(type(pat) == "string", "bad argument #1 to 'new_render' (string expected)"); -- assert(type(escape) == "function", "bad argument #2 to 'new_render' (function expected)"); local function render(template, values) -- assert(type(template) == "string", "bad argument #1 to 'render' (string expected)"); -- assert(type(values) == "table", "bad argument #2 to 'render' (table expected)"); return (s_gsub(template, pat, function (block) block = s_sub(block, 2, -2); local name, opt, e = s_match(block, "^([%a_][%w_.]*)(%p?)()"); if not name then return end local value = values[name]; if not value and name:find(".", 2, true) then value = values; for word in name:gmatch"[^.]+" do value = value[word]; if not value then break; end end end if funcs then while value ~= nil and opt == '|' do local f; f, opt, e = s_match(block, "^([%a_][%w_.]*)(%p?)()", e); f = funcs[f]; if f then value = f(value); end end end if opt == '#' or opt == '%' then if type(value) ~= "table" then return ""; end local iter = opt == '#' and ipairs or pairs; local out, i, subtpl = {}, 1, s_sub(block, e); local subvalues = setmetatable({}, { __index = values }); for idx, item in iter(value) do subvalues.idx = idx; subvalues.item = item; out[i], i = render(subtpl, subvalues), i+1; end return t_concat(out); elseif opt == '&' then if not value then return ""; end return render(s_sub(block, e), values); elseif opt == '?' and not value then return render(s_sub(block, e), values); elseif value ~= nil then if type(value) ~= "string" then value = tostring(value); end if opt ~= '!' then return escape(value); end return value; end end)); end return render; end return { new = new_render; };